Thanks, Ed.
For others, look for or press CTRL F, (MP&E 98-11) in the PDF accessible here, (it is also page 11-57) for what the FRA says.
Here is my original question in the simplest form. It is based on the paragraph quoted from the STB of Canada in my original post. This question has nothing to with the MM&A runaway. This is just logic 101:
Say you are to secure a train on a grade and the rule calls for setting a minimum of 15 handbrakes including those on the locomotives, and then doing a pull test.
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You set the handbrakes, release the automatic brakes, and the train does not move.
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You pull on the train to see if it moves, and it does not move, indicating adequate securement, however, this might be a “false impression.”
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Because you might be getting a false impression, you pull harder and the train moves, which indicates that the first pull gave a false impression.
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You set two more handbrakes, pull as hard as before, and the train does not move.
At this point, what do you conclude? The train might be properly secured—or—you might be getting a false impression. You must rule out the possibility of a false impression that the train is adequately secured. How do you do that? There is no way to do that.
Those valves were only on old 6 axle engines. On the WC we scrapped a bunch of those trucks from the Santa Fe SD45 5300 engines.
4 axle engines are all pretty much the same with truck mounted cylinders.
This depends on a quantifiable, and standardized, “pull”. What’s a “pull”. Is it to be the application of half the weight of the locomotive, or half its tractive effort, or all of its tr
It is a skewing of the results of the test to include the engine brakes in the test, in my inexperienced opinion.
If the engine brakes (and I said “IF”) were able to absolutely lock the wheels against any rotation at all, regardless of the force applied from any source. Then consider that opening the throttle to maximum would only prove that the electric motors on the axles cannot move the engine. The rest of the train could be without brakes and all you know is that the locomotive is incapable of overcoming its own brakes. The rest of the train might be heavy, on a steep grade, on slippery rails, with a tail wind, such that it could cause the locomotive to slide on the rails and the whole train to attain a high speed.
Given that the engine’s brakes may not seize the wheels completely, they are still sapping power from the locomotive in its exertion testing the brakes on the whole train and thus not really testing the holding power of the whole train against all the other forces and circumstances. I don’t know how to calculate the sum of the forces and braking power in such a situation.
I conclude that in testing the brake effectiveness of the cars of a parked train, one should not have any brakes applied on the engine supplying the brake testing power.
But I think that after the test is successfully completed, the engine brakes should be applied just to hold the engine itself. I realize this may make a need to apply more brakes on the following cars than would be necessary if one were to include the Engine axles in the equation, but I see it only as added insurance to holding the train. The various methods of calculating the number of cars to have the brakes set, after lots of multiplication and division by coefficients and fudge factors, they usually include something like " Plus 1" or “Plus 10%” as an additional safety factor anyway. I think the engine brakes could be a part of that "insurance&qu
Class 1 rules that I am familiar with do not permit locomotive hand brakes to be used in the calculations for train securement. Tests will not be performed with locomotive brakes applied, either air or hand. After the securement test is successfully performed on the train, the locomotives will be secured by their hand brake systems.
[BaltACD, I am asking this question pertaining to the securement process that does entail setting the locomotive handbrakes and testing with them set, as the TSB refers to.]
Semper Vaporo,
I think your reasoning is correct, and I also think that it is the basis of the conclusion of the TSB regarding “false impressions.” But I do not think that conclusion is correct. Here is why:
Say you have five engines on a train where the securement calls for 15 handbrakes including the engines. You set the 15 handbrakes and pull on the train. I absolutely agree that the handbrakes on the five engines will reduce the pull that would otherwise come with any given throttle setting without the engine handbrakes set.
I also agree that this reduced pull may not extend all the way through the ten cars with handbrakes set. So you could say that the test is not testing all of the handbrakes that are set for securement. But so what? The only point of the test is to see if the train will move when pulled. And since the locomotives are part of the securement, if the locomotive handbrakes are able to hold the train all
Load Securement
Thanks, Balt, for the laugh. I guess he’s following the rules.
I’m still wondering-- in all the discussion about the bleed valves here, it has been specified that they are on older locomotives. Why are they not on newer locomotives? Are the brakes on newer ones designed differently?
Paul,
When you refer to bleed valves, I assume you mean the QRB valve described in the MM&A runaway report.
I too would like to know the purpose of the QRB valve and related system. The description says that if the locomotive airbrakes (independent brakes) are applied, and a handbrake is applied, the handbrake application trips the QRB valve to release the air brakes on the truck where the handbrake is applied. Why would this be necessary?
It says that if the QRB valve did not perform this air brake release function, the operation of the handbrake application lever would not actually apply the brake. But again, why would the brake linkage be set up this way? Such linkage can be arranged so that either the air power or the handbrake activation wheel/lever will apply the same brake shoes. Yet, on locomotives with the QRB valve, it sounds like the application of airbrakes fundamentally precludes the possibility of apply the same brake by handbrake controls.
So what is the need for that functionality? Not only does it seem pointless, but as the Lac Megantic event shows, a defective QRB valve can result in a trainman applying a handbrake without realizing that no brake has actually been applied.
The valve releases the independent when the handbrake wheel is turned past a give point…we were told it released all of them by our Road Foreman of Engines, but Randy says it only releases the single cylinder it is attached to…I tend to believe Randy.
Anyway, the reason behind it, as we were told, was it forced crews to secure the locomotive with the handbrake first, instead of applying the independent, then spinning the brake wheel till the ratchet stopped and trusting the independent to hold it, when you spun the handbrake wheel, the independent would release, so you had to use the handbrake first….you could then re-apply the independent.
As for why it went away, well, I would assume it was not all that effective, and most railroads adopted new and better rules for securement and testing, plus the advent of Auto Start would have the effect of making it redundant.
For GE, from the old Dash 9 onward, they all have auto start, and EMD from the SD50/60 onward…if you don’t know what you are hearing, having one of the SD 70 MACs with air start unexpectedly fire up next to you can be a little unsettling!
Ed,
Thanks for that explanation. So, as I understand it, the point is that if the independent is applied, a person might not put enough effort into applying the handbrake because they would figure that the independent already has the brake applied adequately. In that illustration, I picture the handbrake lever and the brake cylinder individually connected to a common linkage so either lever-force or cylinder-force (or a combination) would set the brake shoes, similar to the setup on freight cars.
If that is the case, however, I don’t understand is the reasoning behind this functionality as stated in the MM&A report:
“If the QRB valve does not trip, the hand brakes will not provide any braking effort. To ensure that the hand brakes remain operational on these locomotives, MMA issued Summary Operating Bulletin 2-276, which stated in part:
The hand brake will not tighten if the air from the R#2 brake cylinder is not exhausted. The handbrake chain will tighten and it may appear that the handbrake is set however if the R#2 brake cylinder is in the “out” position, the handbrake is not applied. On C-30-7 locomotives if an air exhaust is not heard while tightening the handbrake the QRB valve may be malfunctioning or out of adjustment.”
That seems to be saying that if the air brakes are set, the linkage function of the handbrakes is completely blocked so the handbrake lever will have no effect on setting the brakes. And yet the handbrake lever feedback may feel like the handbrake is being applied even though it is not.
I would think that if the QRB valve do
The handbrake chains pully attachment point is that cylinder’s compound lever, and if the independent is applied, that cylinder is extended and the lever at full travel, applying the hand brake will not tighten the brake shose any more to the wheel than the cylinder piston and lever travel will allow…if the cylinder bleeds down the handbrake will have slack in its chain, so exhaust that cylinder first, apply the handbrake tight, and then apply the independent.
In this image, you can see where the handbrake chain attaches to the brake cylinder lever.
On the older models, if I remember right, it was all inboard, and attached to the other end of the lever.
With this design, you can tighten the handbrake with the independent applied, and if the independent leaks down, it will pull the handbrake chain tighter, the old design was almost opposite of this.
And the center cylinder is not a brake cylinder on this model, it is a weight management cylinder, it lifts the center unpowered axel up off the rail when needed.
The main reason that underslung brake cylinders went away was that the cylinders were suspended between the axles. They were subject to damage from track debris from being so close to the rail.
Most railroads that had them had specific special instructions on operating them. Its quite simple really. As you tighten the handbrake wheel you should hear the air exhausting from the QRB valve and be able to crank the brake wheel an additional amount. Another check is to visually look at the cylinders and see if the #2R piston is in or out, if the piston is out you just tightened the hand brake against the cylinder pressure. If the piston is in and the chain is tight you have a good hand brake.
If the chain is tight and the piston is out you can manually trip the lever on the QRB valve to release the cylinder pressure. Then you must climb back up on the locomotive and tighten the brake wheel some more.
Here’s the same setup on an EMD:
I have been thinking about the QRB valve. I understand the function of the QRB valve. Ed posted a photo showing the handbrake chain relationship to the cylinder in a system where the QRB valve is not used. I can see how that all works and that arrangement seems totally logical. Either the brake cylinder or the handbrake winch can set the brake without one interfering with the other. If both means were applied, either one could be released and the other would continue holding.
However, that apparently is not the case with the alternate linkage system that requires the QRB valve. What I am not certain about how that alternate system of linkage is configured. Maybe a diagram of that linkage could be found. I can see one way of building that linkage, but I don’t know if what I picture is how it is actually built. But it would be sort of opposite the arrangement in Ed’s photo, as Ed mentioned.
My general conclusion is that the alternate linkage serves some purpose in the basic brake cylinder location option; but it also has a fatal flaw in how it interacts with the setting of the handbrake. Therefore to overcome that fatal flaw, the QRB valve is needed.
In the alternate linkage that I visualize, the handbrake could be set after the independent is set, BUT if the independent happens to leak off, the handbrake will be released.
The STB report says this about the QRB valve:
“The hand brake will not tighten if the air from the R#2 brake cylinder is not exhausted. The handbrake chain will tighten and it may appear that the handbrake is set however if the R#2 brake cylinder is in the “
Euclid, I originally got that impression about Ed’s picture, but on further study I think the problem we’ve been talking about still applies.
If I can ask a few questions of Ed or anyone else in the know…
In that picture I assume the brakes are not applied. Is this correct?
On the independent air cylinder at the left, does the piston move to the left when the independent brake is applied?
Does the handbrake pull the chain at the upper right?
If these assumptions are correct, I can see that when setting the handbrake after the independent is applied, you would get little if any movement on the handbrake, and if the independent is released the chain will go slack. Am I seeing this right?
The independent was applied, then the handbrake applied, and the independent was released, to check the handbrake securement, the locomotive stayed put, (we are not allowed to use the independent as a sole means to secure locomotive) and the independent applied again.
Note the cylinder on the far right, the piston is retracted, indication there is no independent application.
When the independent was applied both cylinders had the pistons extended, when the independent was release, the one on the right retracted, but the one on the left cannot retract, the brake chain is holding it out.
On my carrier, the procedure is to stop the locomotive with the independent, apply the handbrake, (we have electric self-applying handbrakes on our locomotives) release the independent to ensure the handbrake is holding the locomotive secure, once assure of that, we re-apply the independent.
In the photograph, the locomotive had been sitting there for a few days, it was bad ordere
[quote user=“edblysard”]
The independent was applied, then the handbrake applied, and the independent was released, to check the handbrake securement, the locomotive stayed put, (we are not allowed to use the independent as a sole means to secure locomotive) and the independent applied again.
Note the cylinder on the far right, the piston is retracted, indication there is no independent application.
When the independent was applied both cylinders had the pistons extended, when the independent was release, the one on the right retracted, but the one on the left cannot retract, the brake chain is holding it out.
On my carrier, the procedure is to stop the locomotive with the independent, apply the handbrake, (we have electric self-applying handbrakes on our locomotives) release the independent to ensure the handbrake is holding the locomotive secure, once assure of that, we re-apply the independent.
In the photo